The law is thus stated in Bennion on Statutory Interpretation 2nd edition, 1992, at pp 860/3:
Ejusdem Generis :Principle:Re-explaned
The ejusdem generis , or "of the same genus" rule, is similar though narrower than the more general rule of noscitur a sociis. It operates where a broad or open-ended term appears following a series of more restrictive terms in the text of a statute . Where the terms listed are similar enough to constitute a class or genus, the courts will presume, in interpreting the general words that follow, that they are intended to apply only to things of the same genus as the particular items listed. Bennion defines the ejusdem generis rule as,
"a principle of construction whereby wide words associated in the text with more limited words are taken to be restricted by implication to matters of the same limited character."
The ejusdem generis rule was applied by O'Higgins J in The People (DPP) v Farrell , in the construction of section 30 of the Offences Against the State Act, 1939 . It was argued that the detention of the applicant in a garda car for a period of hours during the course of his questioning was unlawful and that his subsequent detention in a garda station was therefore also unlawful. The legality of the detention turned on whether a garda car could be regarded as a "convenient place" in accordance with the legislation. O'Higgins J considered that it could not, since the ejusdem generis rule required that the term be construed in the light of the other places of detention listed: "Garda Síochána Station, a prison, or some other convenient place". The rule required, at a minimum, that "other convenient place" should be a building of some kind.
In HMIL Limited (Formerly Hibernia Meats International Ltd) v Minister For Agriculture And Food, the ejusdem generis rule was applied along with the noscitur a sociis rule. Barr J considered that a provision listing "other scraps left over from cutting or boning" at the end of a list of more specific items - bones, cartilages - was "an apposite illustration of the ejusdem generis principle in operation." He found that, according to the rule, "other scraps" should be interpreted as including all unspecified items which were not fit for human consumption."
More recently, the presumption was applied in the High Court by Barr J in Royal Dublin Society v Revenue Commissioners. Barr J held that section 7 of the Excise Act, 1835 , which allowed the Revenue Commissioners to grant a liquor licence to " ... a theatre or other place of public entertainment" was a provision to which the ejusdem generis rule applied. He found that there was nothing in the Act to suggest that "other place of public entertainment" was meant in a wider sense to that applicable to "theatre" and that therefore it should be interpreted only as referring to places of public entertainment which were similar to, or within the same genus as, "theatre", in other words to "a performance for the benefit of the public with a defined time frame and where seating is provided for patrons."
The ejusdem generis rule will not apply where there is a list of items which do not constitute a genus, or where only one item is listed. In Kielthy v Ascon Ltd it was emphasised by O Dalaigh CJ that the ejusdem generis rule could only apply where antecedent categories establish a genus. He held that this was not the case where, as in the provision to be interpreted by the court, the general words were preceded by the enumeration of only one category. In Dublin Corporation v Dublin Cinemas Ltd it was held that a list of words in a statute which included playgrounds, recreation grounds and "any building adapted for use as a shop" was too broad and included items which were too incongruous to constitute a genus, and that therefore the ejusdem generis rule did not apply.
The courts will also refuse to apply ejusdem generis where a statute contains general words, which are then followed by a list of particular items: in such cases the list of items is not regarded as limiting. In Application of Quinn , Griffin J pointed out the limitations of ejusdem generis , and emphasised that it was a presumption rather than a rule: "...the ejusdem generis rule is one to be applied with caution as it is a mere presumption which applies in the absence of any other indications of the legislature." He found that the ejusdem generis presumption did not apply to the construction of section 2 of the Public Dance Halls Act, 1935, since the general words preceded the particular words, rather than followed them.